Polyarylene sulfides are high-performance polymers that may withstand high thermal, chemical, and mechanical stresses and are beneficially utilized in a wide variety of applications. Polyarylene sulfides are generally formed via polymerization of a dihaloaromatic compound such as p-dichlorobenzene with an alkali metal sulfide or an alkali metal hydrosulfide, forming polymers that include a halogen, generally chlorine, at the terminal endgroups. With low halogen content polymers becoming increasingly desired due to environmental concerns, attempts have been made to produce low halogen content polyarylene sulfides.
Post-polymerization washing with conventional materials including water, salt solutions, and/or certain organic solvents has proven effective for removal of ionic chlorine from polyarylene sulfide, but is not adequate for removal of chlorine covalently bound on the polymer chains. Other methods that have been devised for chlorine removal include reaction of the formed polymer at high temperature and pressure conditions. Unfortunately, such methods require process conditions that are not practical or cost effective in industrial applications. In addition, previously known methods can degrade the polymer backbone, which can affect product characteristics.
What are needed in the art are polyarylene sulfides that have a low halogen content, and particularly low chlorine content. In addition, what are needed are facile, straightforward methods for forming low halogen polyarylene sulfides that do not require complicated or extensive processing steps and will not degrade the polymer backbone.